The islands of the Philippines slowly emerged from the surface of the Pacific ocean.
Based on Tectonic Plate Theory, a very huge earthquake and a strong volcano eruption under the China Sea happens some 225 million years ago. The lava and mud that erupted had slowly hardens and that becomes land in the surface of the ocean. Several strong earthquake also happens which pushes and scatters the land masses that was formed by the volcanic eruption. This now becomes the 7,107 islands that makes up the Philippines.
However on Sunda Shelf Theory, this explains that the Philippines is once part of the Sunda Shelf. The Sunda Shelf is a huge part of the Continent of Asia (at least 1,800,000 square kilometers) that was projecting high in the surface of the ocean. About 45,000 years ago, after the Ice Age, the melted ice had swell the ocean and engulfed the land bridges that connects the Philippines to the rest of Asia.